Conventional hack saw frames generally have a proximal handle (closer to a user's hand), a distal portion (farther from a user's hand, relative to the proximal handle), and an elongate upper frame arm extending between the upper ends of proximal handle and distal portion. The hack saw defines a generally planar shape. Each handle defines a mounting slot/cavity adjacent a lower end thereof, through which projects a blade mounting pin holder, for releasably mounting a hack saw blade therebetween. Generally, at least one of the blade mounting pin holders also operates as a blade tensioning mechanism, through which tension is applied to the blade, to keep the blade rigid to assist in straighter cuts and longer blade life.
In use, a user manually applies push and pull strokes to the hack saw, in a plane of motion, to cut through a work piece. Usually, the cut is aligned with the plane of motion. On occasion, a cut must be made that is not aligned with the plane of motion. For example, space constraints or interference may prevent proper orientation or movement of the saw. As another example, a work piece surface may have an object protruding therefrom that requires removal, such as a work piece surface having a pipe projecting therefrom that requires cutting at the base thereof, i.e., at the interface between the pipe and the work piece surface. In such a case, the hack saw cannot be oriented to cut through the object, e.g., transversely through it, due to interference between the hack saw and the work piece. To make the cut, the user must orient the height of the blade in a plane substantially parallel to the plane of the work piece surface, i.e., in a plane perpendicular, or at some other angle, to the plane of motion. The blade may then be placed substantially flush with, and adjacent to, the work piece surface and cut through the base of the projecting pipe. Normally, however, a blade is mounted in a hack saw frame, such that the height thereof orients in a plane parallel to the plane defined by the saw and the plane of motion (and perpendicular to the work piece surface). Thus, for example, the blade must be rotated, e.g., approximately 90°, to be oriented substantially parallel to the work piece surface. To mount the blade to the frame in this rotated orientation, the tensioning mechanism and the blade mounting pin holder, to which the blade is secured, must also be rotated.
In some saws, the tensioning mechanism is not rotatable within the mounting slot through which it projects. For example, the tensioning mechanism and mounting slot are cooperatively shaped, e.g., keyed, so that it cannot rotate in the slot. One reason for this is to ensure that the tensioning mechanism does not rotate and thereby misalign the blade secured thereto during use of the hack saw. Thus, to rotate the blade, the tensioning mechanism is separated from the hack saw frame (i.e., from the respective slot to which it is assembled), independently rotated, and then reassembled to the hack saw frame. At a minimum, such separation, to rotate the tensioning mechanism is a nuisance to the user as it renders the process more difficult and/or time consuming.
In other saws, the tensioning mechanism is freely rotatable within the mounting slot of the handle through which the tensioning mechanism projects. Thus, the tensioning mechanism can rotate within the mounting slot without separating therefrom. However, as mentioned above, one drawback associated with this approach is a potential problem with respect to maintaining proper alignment of the tensioning mechanism, and thus the blade. A freely rotatable tensioning mechanism is also susceptible to misalignment during assembly. For example, the tensioning mechanism may be initially assembled to the mounting slot in an incorrect orientation. Even if initially assembled oriented properly, the tensioning mechanism is susceptible to rotating/twisting while applying tension thereto, thereby misaligning the tensioning mechanism. Such misalignment will result in misalignment of the hack saw blade secured thereto.